1. Technical Field
The present invention relates to a timepiece having an electrophoretic display panel.
2. Related Art
Electrophoretic display panels that use electrophoresis, which is a method of applying an electric field to cause charged particles dispersed in a liquid medium to migrate to a particular electrode, and display devices that use electrophoretic display panels are known from the literature. Such electrophoretic display panels have this dispersion of charged particles sealed between a substrate on a front surface side and a substrate on a back side, and the display panel can be made flexible by using flexible substrates. This can be used to render a wristwatch that has a display panel such as this electrophoretic display panel disposed around the outside of a ring-shaped bracelet as taught, for example, in Japanese Unexamined Patent Appl. Pub. JP-A-2005-250442, paragraph [0022].
As described in Japanese Unexamined Patent Appl. Pub. JP-A-S54-151056, the display part of this type of electrophoretic display panel has a plurality of display units (segments) corresponding to each of the characters used to display the time or other content, a segment electrode is provided on one of the substrates for each of these segments, a common electrode is provided on the other substrate, and a voltage is applied between these electrodes to display information. In order to display the numbers 0 to 9 that are needed to display the time, for example, the digit 8 is rendered with 7 or 13 substantially rectangular segments, and the same number of segment electrodes are rendered on the one substrate. Each of these segment electrodes can be separately driven according to the time information to refresh the display rendered in the time display area where these segments electrodes are disposed as time progresses.
This segment display method, however, requires 7 or 13 segment electrodes for each character that is displayed. With the development of flexible electrophoretic display panels and the ability to render the display panel around the outside of a ring-shaped case as described above, the display panels have become much larger. When this large display area is used to display numerous characters each rendered with 7 or 13 segments to display more information or patterns, the number of pins required to drive the characters increases significantly. Because the number of output pins on the drive circuit of the display panel is limited, rendering such displays becomes difficult and the wiring is complicated. In other words, while demand for larger display panels continues to rise, there is a limit to what can be practicably achieved with conventional segment display methods.
In addition, because conventional segment display methods display each character using a combination of 7 or 13 segments, the numbers or letters that are displayed are uniform and the designs that can be displayed are limited.